2007 honda crf 450r help needed

hi there

  recently I purchased a 2007 Honda crf 450r with a blown motor.  I replaced everything but the cases, ( new crank, big bore cylinder, piston, rings) after assembling the engine and ridding it im having a issue with oil filling up the breather line that goes from the valve cover "T's" and goes to the air box and the other is a drain hose with a plug in it.  I have put the recommended amount of oil per the manual did not over fill it..not having any issues with the oil in the trans side lowering. the amount of oil that im loosing out the hose and air box is the same amount of oil that is missing from the engine side of the cases. the piston ring is installed the correct way.  the reed valve in the case is installed the right way and functions when light air pressure is applied to the system.  can any one shed some light or help me out with what they might think is causing this issue


  thanks I hope to get this issue solved

If the engine is a fresh rebuild, it may need to seat the rings a bit before this stops.

I would also check the breather as in the link above. Make sure its breathing and not plugged.

See what happens then.

I'm guessing you didn't install your piston rings correctly and are getting blow by causing the pressure to push oil out of the valve cover. Your gonna new new rings, head and base gasket.

I have replaced the new rings and gaskets..also gave the cylinder a quick ball hone

The recomended amount of oil when you filled it up is fine and all that, but I think youve got the right side crank seal out and its sucking the oil out of the trans and over filling the engine side, not to mention draining the trans.

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